Kolkata: A steady north-westerly breeze improved Kolkata's ambient air quality on Tuesday, countering the adverse effects of falling temperatures and thermal inversion that typically trap pollutants close to the ground during winter.
While the mercury continued its downward slide, the movement of air helped disperse pollutants, preventing a sharp deterioration in air quality. While one monitoring station (Salt Lake) remained in the satisfactory category (AQI 51–100) for most of the day before slipping into the moderate range by evening, four other stations stayed within the moderate zone (AQI 101–200).
A 10–20 kmph breeze not only intensified the chill but also prevented the formation of dense fog — an annual winter hazard for the city. As a result, operations at the Netaji Subhas Chandra Bose International Airport continued without disruption. Visibility at the airport briefly dipped to 400m at 7.30 am and fell further to 200m by 8 am. However, conditions improved steadily thereafter, rising to 400m by 8.30 am, 700m at 9 am and nearly 900m by 9.30 am. Airport officials said the presence of a Category-III ILS, which allows operations even at visibility as low as 50m, ensured there were no delays.
Meteorologists attributed the unusual clarity to prevailing wind patterns rather than typical winter weather systems. "The temperature is steadily going down. On Tuesday, the Dum Dum observatory recorded a minimum of 9.5°C," said G K Das, head of the Dum Dum Met office. "Kolkata usually experiences radiation fog, which forms after rainfall linked to western disturbances. This year, however, strong north-westerly winds prevented fog formation."
Experts cautioned that while the breeze offered temporary relief, prolonged calm conditions or further temperature drops could worsen air quality in the coming days.